As high-voltage and high-energy density batteries, for example, Li ion batteries are known. The Li ion battery is a cation-based battery utilizing a reaction between a Li ion and a cathode active material and a reaction between a Li ion and an anode active material. Meanwhile, as anion-based batteries, fluoride ion batteries utilizing a reaction of fluoride ions are known.
Solid electrolyte materials used in fluoride ion batteries are known. For example, Non Patent Literature 1 discloses that La1−yBayF3−y (0≤y≤0.15) having a Tysonite-type structure has fluoride ion conductivity.